This invention relates to pipe repair clamp-couplings for servicing pipe lines by closing over leaks and for joining together sections of pipe. The prior art provides repair clamps comprised of semi-cylindrical body members joined together to form a cylindrical sleeve or coupling member that surrounds and/or joins the pipe. The body members interface at a diametrical axially disposed plane, and each member carries separate semi-circular and longitudinal gasket members to seal the opposite semi-circular ends of the assembled clamp, and to seal along the opposite interfaced sides of the body members. When these coupling members are assembled and clamped onto a leaky pipe, the circumferential and longitudinally disposed gaskets seal against the outside diameter wall of the pipe and stop leakage embraced thereby.
In order to facilitate and ensure a proper clamp-coupling assembly, so called "girdering" has been provided to prevent displacement of the gasket-seals from working position, as may be caused by scraping or by subjection to high velocity high pressure fluid discharge from or through the pipe under repair. Heretofore, girdering has been in the form of a series of thin separated metal plates supported axially from a sheet metal strip attached as by welding to the inner diameter of the coupling members, so as to extend partially over the gasket-seals to retain them in position. When the clamp-coupling is assembed over the pipe, the gasket-seals are compressed so as to produce a fluid tight seal and the girdering plates are firmly pressed against the outer pipe diameter walls leaving an interstice between the clamp members and outer pipe circumference commensurate with the thickness of the girdering sheet metal strip.
A deficiency in the separated girdering plates of the prior art is that the circumferential separation of the metal retaining plates and supporting strip permits the gasket-seal material to be extruded from its positioning groove by internal fluid pressure within the pipe line and clamp-coupling, it being an object of this invention to eliminate the aforesaid insterstices and to confine the gasket-seal material to its positioning groove so as to preclude said extrusion of the gasket-seal material by eliminating said girdering plates and the separation therebetween.
Deterioration of pipelines and their various fittings and repair clamp-couplings is a serious problem that repeats itself in pinholes and structural weaknesses and eventual leakage and other such failures. Deterioration can be found as the result of; 1) normal exposure to an environment; 2) service in the transport of corrosive or incompatible and/or destructive fluids (gas or liquid); and 3) electrolysis and its anodic effect.
With respect to 1) above; normal service may involve heat to cold exposure, dry to wet exposure; fresh water to salt (Saline or toxic) water exposure, or any combination thereof, and all of which in time will destroy a pipeline installation.
With respect to 2) above; the clamp-coupling wall structure may be consumed by corrosion or by chemical reaction so as to destroy support for the aforementioned gasket-seal, resulting in failure.
With respect to 3) above; the clamp-coupling wall structure may be eaten away by electrical discharge so as to remove support for the aforementioned gasket-seal, resulting in failure.
It is these basic detrimental factors which this invention addresses, in order to improve pipeline repair clamp-couplings and greatly increase their longevity and reliability.
State of the art pipeline repair clamp-couplings are fabricated of steel and comprised of rolled sections and planar flanges and welded together and machined as required to present the aforesaid separate circumferential and langitudinal gasket-seal grooves. These completed clamp-coupling assemblies include these separate gasket-seal, installed and secured in said grooves by the thin sheet metal girdering. And, all of which is characteristically unprotected against oxidation and subject to corrosion in a normal environment. In practice, the sheet metal girdering deteriorates even without exposure to an adverse environment. As a result, unprotected clamp-couplings of the type under consideration become faulty while stored in an equipment depot or warehouse. Therefore, it is a general object of this invention to protect pipeline clamp-couplings from the normal environment, so that they remain reasonably fresh and do not quickly deteriorate. Accordingly, internal areas of this clamp-coupling are coated with a barrier impervious and/or resistant to the corrosive or chemical effect of the atmosphere.
It is common practice for piplines to transport sour gas/sour oil, salt solutions, and mixtures containing sulfites, sulfates, sulfuric acid, etc. Such pipelines are in use in petroleum/gas production and refining, and in the chemical and related processing industries. Accordingly, there is a multitude of corrosive and chemically active fluids transported by pipeline over short as well as long distances. And, for any fluid, whether common or exotic, there are materials and particularly coatings which are impervious, inert or at least resistant thereto. For example, Electroless Nickel Plating is an electrically conductive protective coating; whereas TEFLON (.TM.) (sprayed and baked on) is a non-conductive protective coating. It is to be understood that there are many different methods of plating and/or coating that are to be employed in practicing this invention, selected according to compatibility with the transported fluid. The coating employed for each transported fluid product is therefore selected as circumstances require, providing that it qualifies as impervious, inert or resistant to the product fluid. However and in accordance with this invention, when employing an electrically conductive fluid barrier, only the surfaces exposed to the product fluid are coated, thereby eliminating the possibility of the clamp-coupling becoming anodic. But with non-conductive coatings the entire interior of the clamp bodies can be coated, providing it does not interfere with the introduction of and retaining of the gasket-seals. Therefore, it is an object of this invention to selectively coat only those areas of the clamp bodies which are exposed to the product fluid, when conductive coatings are employed, thereby reducing the effect of electrolysis.
The gasket-seal employed herein follows the teaching of the art, and is essentially a gasket by virtue of its flat sided configuration for sealing between opposing planar surfaces. And, as a seal it has a cross section of substantial thickness with a body volume adapted to be compressed so as to tightly flow into and fill a seal groove of the same cross section. The semi-circular end gasket-seals are angularly abutted and fused to the longitudinal side gasket-seals, for seal continuity without interruption.
In accordance with this invention, there are opposite end semi-circular gasket-seal retainers positioned by semi-circular anchor grooves, and the opposite side longitudinal gasket-seals are cemented into position in complementary longitudinally siposed seal grooves. The semi-circular gasket-seal retainers have a coextensive anchor portion received by the groove configuration for positioning a continuous rim thereof over the edge of the semi-circular gasket-seals, it being an object to provide such a gasket-seal retainer and gasket-seal reliably captured in position thereby.
In accordance with this invention, the deficient prior art sheet metal separated plate girdering and welding is replaced by the impervious gasket-seal retainer characterized by its continuous rim and anchor captured in the anchor groove formed in the clamp bodies. In practice, dove-tail anchor grooves are formed in the inner diameter wall of the clamp bodies, there being a semi-circular anchor groove at each opposite end of the clamp bodies for the end gasket-seal retainers. The semi-circular gasket-seal grooves and anchor grooves open into longitudinal seal grooves at opposite sides of the clamp body for gasket-seal continuity without interruption. The anchor grooves are machined and/or formed into the inner diameter walls of the clamp bodies, and the semi-circular gasket-seal retainers are flexible and extruded or injection molded plastic of material selected for tolerance to the product fluid being transported by the pipeline, for example TEFLON(.TM.) or the like.